Heat exchanger



J. P. RATHBUN HEAT EXCHANGER Filed May 17 June 22, 1937.

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2 Sheets-Sheet June 22, 1937. l l J. P. RATHBUN 2,084,743

-- f HEAT. ExcmNGER Filed lay 17, 1955 2 sheets-sheet 2 /ITNEssEs:lNvErJ'roR H JoHNPRATHBuN fm l l FIGJO. (Xndbwl.

ATTORNEY Patented June 22, 1937 PATENT OFFICE HEAT EXCHANGER John P.Rathbun, Prospect Park, Pa., assignor to Westinghouse Electric &,Manufacturing Company, East Pittsburgh, Pa., a corporation ofPennsylvania Application May 17,

` 13 claims.

My invention relates to heat exchange apparatus, more particularly toheat exchange apparatus in which one iiuid is at least partiallyvaporized, and it has for an object to provide improved apparatus.

A further object is to improve the heat transfer rate of such apparatus.

l In accordance with my invention, I provide a shell or other vessel inwhich there are disposed heating elements, such as tubes containingheatlng iluid. Bafiles are arranged to provide a plurality of passagesthrough which liquid ilows upwardly in contact with the heating elementsto be heated thereby.l Other passages convey the iluid, out of Contactwith the heating elements, from the upper ends of heating passages tothe lower ends of the heating passages. The vapor formed in each heatingpassage is removed through the upper `portion of the shell. Thus,V

natural convection currents are utilized to provide maximum flow andheat transfer.

The above and other objects are effected by my invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawings, forming a part of this application, inwhich:

Fig. l is a plan view, partly in section, of one embodiment of theapparatus;

Fig. 2 is a vertical longitudinal section thereof;

Figs. 3, 4, and 5 are transverse sectional views taken on the linesIII-111, IV-IV, and VV, respectively of Fig. 2;

Fig. 6 is an enlarged broken perspective view showing the bailles; AFig. 'l is a vertical longitudinal section of a Amodied form of heatexchanger;

Figs, 8 and 9 are transverse sectional views taken on the linesVIII-VIII and lX-IX of Fig. 7; and

Fig. 10 is a fragmentary section of a modified baule construction.

' Referring to the drawings in detail, the heat exchange apparatuscomprises a cylindrical shell Il which may have an integral closure IIat one end. The shell l0 contains' tubes I2 and I3 for circulatingheating fluid, the tubes being arranged in a nest or bundle in the lowerportion oi?A ,the shell, that is, somewhat below the top of the shell,as shown on the drawings. The tubes are secured at one end to a tubesheet I4, which is clamped between a flange l5 of the shell III and aflange I6 of a removable head I'l. The latter comprises an inlet chamberI 8 having an inlet connection I9 and an outlet chamber 2| havlng anoutlet connection 22. at the opposite 1935, Serial No. 22,085

end, the tubes are secured to a floating tube sheet 23, to which aoating head 2l is secured. The floating head 24 provides a reversingchamber for directing the heating iluid from the tubes I2 to the tubesI3. It is to be understood that any suitable heating fluid may be used.For example, steam may be used as contemplated by the illustratedembodiment, in which case the tubes I2 may be greater in number than thetubes t3. The steam gives up its latent heat in the tubes I2 and thetubes I3 serve primarilyfor returning the condensate to the head I1. Itis to be understood that any desired number of tube passes and any otherdesired arrangement of tube nest may be used.

As shown in Figs. 4 and 5, the -tube nest is spaced from the cylindricalwall of the shell Il, and curved bailles 25 partially enclose the tubenest, extending about the sides and partly about the bottom of the tubenest and providing downwardly extending passages 26 between the tubesand the cylindrical wall of the shell. The upper edges of the bafiies 25extend approximateely to the top of the tube nest, and the lower edgesextend-to the bottom of the tube nest but are in spaced relation to eachother so as to provide communication between the lower ends of thepassages 26 and the tube space which is partially enclosed by thebaiiies 25. The tailles 25 may be continuous, as in the illustratedembodiment, extending from the tube sheet I4 to the ytube sheet 23.

'I'he tube space Vis divided transversely of the tubes, by two groups ofbales, 28 and 29, arranged alternately, into a plurality of compartmentsI6 and a plurality of compartments 4l, arranged alternately. As shown inFig. 4, the baille 28 comprises a member 30 which is disposed betweenthe baiiles 25 and which is slightly more than semi-circular in Yform.It further comprises an approximately semi-annular member 3l extendingbetween the bailies 25 and the shell up to the height of the bailles 25.Thus, the baille part 30 extends upwardly above the part 3l, to formslots 32 as shown in Figs. 4 and 6 for ilow of liquid, as hereinafterdescribed. The baille parts 30 and 3| are secured, to each other andtothe baffles 25 in any suitable manner, as by welding. They togetherVform tube supports adapted to slide on the bottomv of the shell.

. The transverse bafiles 29 comprise a central baille part 33, similarin form to the baille part 30, also extending upwardly above the tubenest. It further comprises arcuate parts 34 between thefbaies 25 and theshell. The parts 34 extend upwardly to the upper edge of the part 33vand extend downwardly only to the lower edges of the bafes 25, therebyforming a port 35 in the bottom of the bale 29, through which liquid mayiiow from one compartment 41 to the next' compartment 46.

The entire tube bundle, including the baiiles, may be removed as a unitthrough the left hand end of the shell upon disengaging the iianges I6and I5.

'I'hevshell is provided with a liquid inlet 36 in the bottom thereof inthe end adjacent the head structure I1 and with a liquid outlet 31 atthe other end. It is formed with a vapor outlet 38 in the upper portionthereof adjacent the end wall I I. A lweirrlilmay be provided adjacentthe floating head 24 to insure complete subm;rgence of the tubes in theliquid, and the shell may be Aextended beyond the weir 39 to provide astorage chamber 4I for liquid leaving the shell. A baille 42 may beprovided at the top of the shell between the Weir 39 and the vaporoutlet 318 and provided with a trough 43 adapted to collect and drain tothe cylindrical wall of the shell any liquid particles collected by thebaille 42. A liquid separator 44 may be provided at the vapor outlet 38to separate out any liquid particles carried in suspension by thevaporleaving the shell. The liquid may be drained through a conduit 45into the storage chamber 4I.

The.operation of the above-described `apparatus is'as follows: while theabove-described apparatus is useful generally for vaporizing liquid; itis particularly adapted to be used as a reboiler in oil refineryapparatus, to separate a component or components of lower boiling pointfrom a component or Icomponents of higher boiling point. Naturalconvection or thermosyphonic circulation of liquid in each compartment46, 41 is eifected by the heating action of the tubes I2, I3, the liquidflowing upwardly through the space between the baiiies, over the upperedges of the baiiles 25, downwardly through the passages 26 around thelower edges of the bailies 25 back into the space between the bailles25. In each of the compartments 46, 41, a portion of the circulatingliquid is continually passed on to the next compartment and added to theliquid circulating therein, as will now be described. The liquidcontaining a mixture of components of both higher and lower boilingpoints is admitted to the shell I0 through the inlet 36 into the firstcompartment 46. It joins the liquid coming down through the passage 26,and the mixture iiows upwardly through the passage provided between thelower edges of the baffles 25 into the tube space enclosed by saidbaiiles. As it iiows upwardly itl comes in contact with the heatingtubes I2 and I3 and is heated thereby. As it reaches the top of the tubenest, the components of lowest boiling points, or lighter fractions,vaporize and flow olf into the vapor space formed in the upper portionof the shell above the tube nest. One portion of the liquid rising tothe top of the tube nest spills over the upper edges of the baiiles 25and flows downwardly through the passages 26. From the latter, it isagain admitted through the passage between the lower edges of thebaffles 25 to the tube lspace enclosed by said baiiies and isrecirculated as described. Another portion of the liquid rising to thetop of the tube nest spills over the upper edges of the baffle parts 3|,through the notches 32, into the next compartment 41 between the baliles28 and 29.

In the compartment 41, the liquid flows downwardly through the passages26 to the bottom of the shell. One portion of the liquid then iiowsupwardly through the tube space of the compartment 41, and anotherportion ows through the port 35finto the next compartment 46 betweenbailies 29 and 28. The portion of the liquid owing upwardly through'thetube space in the compartment 41 spills over the upper edges of thebaiiles 25, giving off to the vapor space the vapor formed as it ispassed over the tubes, and again passesl downwardly through the passages26. The portion of the liquid passing through the port 35 joins theliquid in the next compartment 46 which is flowing upwardly through thetube space.

The liquid then flows successively through the remaining compartments 46and 41 in the same manner as just described, the components ofsuccessively higher boiling points being gradually vaporized. From thelast port 35, the liquid flows upwardly over the ends of the'tubes I2and I3 and the oating head 24, and spills over the upper edge of theWeir 39 into the storage chamber 4I, from which it is withdrawn throughthe outlet 31. Y

In the above arrangement, the liquid iiows upwardly in contact with theheating tubes and downwardly out of contact with the tubes, therebysetting up natural convection currents within each compartment,resulting in increased rate of fiow and increased rate of heat transfer.The iiow from one compartment to the next is effected by gravity, theliquid'being admitted under pressure and rising to a sufliciently highlevel in the rst compartment to effectA such ilow, the' liquid levels inthe successive compartments being successively lower.

In Figs. 7, 8, and 9, I show a modied baiiie arrangement, the remainderof the structure being the same as in Figs. 1 to 5. A curved baiilemember 5I extends about the sides and bottom of the tube nest in spacedrelation to the wall of the shell, providing passages 52 and 53, shownin Figs. 8 and 9, respectively. The baffle member 5I may be continuousbetween the tube sheets. The tube space is divided by transverse baflies54 into compartments 55. The balile 54, as shown in Fig. 9, comprises anintermediate member 56 having openings through which the tubes extendand arcuate members 51 between the circular member 5I and the shell I0.Ihe lower edges of the latter are in spaced relation to form a port 58,while the upper edges of the parts 56 and 51 are spaced a short distanceabove the top of the baille member 5I and the tube nest. As shown inFig. 8, an arcuate baille member 59 between the curved baille member 5Iand the shell provides a division Wall between the passages 52 and' 53,and extends continuously from one side to the other to a height evenwith the top edge of the baille member 5I. The curved baille member 5Iis formed with a slot 6I in the bottom thereof In the part of eachcompartment 55 adjacent the passage 52, that is, from the tube sheet I4or the baille 54 to the baille 59, while it is continuous adjacent thepassage 53, that is, from the the weir 39. f f

10 through the slot 6iu into the tube space.

wardly. joins tlie liquid entering through the inlet 35, and rechtersthe tube space through the slot 8l. The flow of this portion is effectedby the natural convection or thermo-syphonic circu- -5 lation induced bythe heatingaction of the tubes. The portion of the liquid entering thepassage 53 flows downwardly to the bottom thereof and/then through theport 58 in the baille 54 into the next compartment. In the latter, itflows upwardly The cycle of operation just described is then repeated ineach compartment. From the last port 58, the liquid ows upwardly overthe ends of the tubes andthe floating head 2l and spills over In thisembodiment, the liquid flows upwardly in contact with heating tubes anddownwardly out ofcontact therewith as in the rst embodiment. Thepassages 52 provide recirculation of liquid within the severalcompartments, while the passages 53 provide for flow from onecompartment to the next. In this case, the convection currents throughthepassages 53 assist the gravity flow of the liquid from the inlet tothe outlet end of the tube space, since the head of the heavier unheatedliquid in the passages 53 exceeds the head of the lighter boiling liquidilowing upwardly into the tubes in the next compartment. C A

As shown in Fig. l0, the curved bailies 25a may be made in sections soas to be removable. Each of the transverse bailles 28a and 29a isintegral, instead of comprising separate parts as in Figs. 4 and 5. Eachbaffle section 25a extends between adjacent transverse bailles and isdetachably secured thereto by angle members and bolts shown at 62. Uponremoving the curved baille sections 25a, access to the tubes is providedfor periodically cleaning the same. In all other respects, the baillestructure of Fig. 10 may be the same as that shownin Figs. 1 to 6.

A :further advantage of the present invention is that all oi the liquidis caused to rise repeatedly to the surface, at least once in eachcompartment, where the vapor separates from the yliquid to a muchgreater extent because of the low hydrostatic head.

While I have shown my invention in several forms, it will be obvious tothose-skilled in the` 50` art that it is not so limited, but issusceptible of various other changes and modications without departingfrom the spirit thereof and I desire, therefore, that only suchlimitations shall be placed thereon as are imposed in the prior art oras are set forth in the appended claims.

What I claim is:

1. In heat exchange apparatus, the combination of baille means providinga plurality of circuits each comprising a downwardly extending passageand an upwardly-extending passage, means for heating the liquid in theupwardly extending passage to vapcrize a portion of the liquid andthereby to effect thermo-Siphonic circulation of the liquid in thecircuit, a dome or vapor space communicating with the upper portions ofthe several upwardly-extending passages for receiving thel vaporizeduid, and means for conveying at least a portion of the liquid from onecircuit to the next.

2. In heat exchange apparatus, the combination of a shell, heatingelements within the shell. baule means within the shell providing aplurality of upward passes for liquid to be heated in contact with saidheating elements and a plurality of 75 downward passes out of contactwith the heating elements and arranged to provide iiow of liquid througha plurality of upward passes successively, the liquid flowing throughupward and downward passes alternately, the upper portion of theinterior of the shell constituting a vapor space in communication withthe upper ends of the several upward` passes and receiving the vaporformed therein.

3. In heat exchange apparatus, the combination of a shell, a tube nesttherein, baiiles disposed transversely of the tubes and providing a.plurality of compartments, other bafiles in the compartments providingrst vertical passages through which the tubes extend and second verticalpassages substantially without tubes, the vertical passages in eachcompartment being in communication at the upper ends whereby liquidflows upwardly in the first passages and then downwardly in the secondpassages, a plurality of said transverse bailies having a port providingcommunication between the lower ends of the second passage of onecompartment and the first passage of the next compartment to provideflow of liquid successively through the compartments. l

4. In heat exchange apparatus, the combination of a shell, a tube nesttherein, baiiies disposed transversely of the tubes and providing aplurality of compartments, the tubes being arranged to provide rstvertical passages through which the tubes extend and second verticalpassages substantially without tubes, the vertical passages in eachcompartment being in communication at the upper ends whereby liquidflows upwardly in the rst passages and then downwardly in the secondpassages, a plurality of said transverse bailies having a port providingcommunication between the lower ends of the second passage of onecompartment and the rst passage of the next compartment to provide ow ofliquid successively through the compartments.

5. In heat exchangeapparatus, the combination of a shell, a tube nesttherein, baffles disposed transversely of the tubes and providing aplurality of compartments, vother bailles in the compartments providingrst vertical passages through which the tubes extend and second verticalpassages substantially without tubes, the vertical passages in eachcompartment being in communication at the upper ends whereby liquid owsupwardly in the first passages and then downwardly in the secondpassages, and means providing flow of liquid successively through theseveral compartments.

6. In heat exchange apparatus, the combina.-

contact with said tubes while flowing longitudinally of the shell fromthe inlet to the liquid outlet.

7. In heat exchange apparatus, the combination of a shell, a tube nestwithin the lower portion of the shell, the upper portion of the shellconstituting a vapor space, an inlet for admitting liquid adjacent oneend of the shell, an

outlet for withdrawing liquid adjacent the other end of the shell, avapor outlet communicating with said-vapor space, and a baille orbaiiies disposed transversely of said tubes between said liquid inletand said liquid outlet and providing a plurality of compartments for theliquid owing between said inlet and outlet, said tubes being arranged toprovide lanes for .ilow of liquid. from 5 the top of the tube nest tothe bottom thereof,

and said bailles being formed to provide communication between adjacentcompartments in such manner that the liquid flowing from the liquidinlet to the liquid" outlet flows upwardly in contact with the tubes atleast oncein a plurality of said compartments.

8. In heat exchange apparatus, the combination of a shell, heatingelements within the shell, baille means within the shell providing aplurality l5 of passages for ilow of liquid upwardly in contact withsaid heating elements and a plurality of downward passages for ilow ofliquid downwardly out of contact with heating elements, said baillemeans being arranged to provide ilow of liquid through said heating anddownward passages alternately and to provide ilow of liquid upwardly atleast once through each of a plurality of said heating passages, andmeans for removing vapor from the liquid at the upper end of eachheating passage.

9.`In heat exchange apparatus, the combination of a shell having aliquid inlet and a liquid outlet, a bundle of tubes arrangedhorizontally in the shell, baiiles arranged transversely of the tubesand dividing the tube containing portion of the shell into compartmentsthrough which liquid ilows successively from said liquid inlet to saidliquid outlet, the liquid flowing upwardly through each compartment incontact with said tubes, and means providing a passage for ow of liquidwithin the shell and out of contact with tubes from the top of onecompartment to the bottom of the next compartment, and means forremoving vapor from the liquid at the top of each compartment.

10. In heat exchange apparatus, the combination of a shell, a tubebundle arranged horizontally within the shell, bailies arrangedtransversely of the tubes and providing a plurality of passes ilow ofliquid within the shell out of contact with to provide space for flow ofliquid downwardly within the shell from the top to the bottom of thetube bundle substantially out of contact with tubes, means includingtransverse baflles in said space providing passages arranged to conveyliquid from the top of one heating pass to the bottom of another heatingpass to cause liquid to ilow through a plurality of said heating passessuccessively in iiowing from saidv liquid inlet to s aid liquid outlet,and means for removing vapor from the liquid at the top of each heatingpass.

12. A heat exchanger comprising a shell having a liquid inlet and avapor outlet, a bundle of heating tubes disposed horizontally therein,

vbailles disposed transversely of the tubes and dividingl the tubecontaining portion of the shell into compartments through which liquidows successively, said tubes being arranged to provide lanes for flow ofliquid from the top to the .bottom of the tube bundle out of contactwith tubes, said baffles providing a liquid inlet for each g of aplurality oi said compartments only at the bottom thereof and a liquidvoutlet for each of said plurality of compartments only at the topthereof, whereby liquid is caused to ilow 'upwardly at least oncethrough each ofsaid plurality of compartments in contact with theheating tubes therein.

13. In heat exchange apparatus, the combination of a shell having aliquid inlet, a liquid outlet, and va vapor outlet, a group of heatingelements within the shell, and baille means causing the liquid to owfrom the bottom to the top of the group of heating elements a pluralityof times in owing from said liquid 'inlet to said liquid outlet.

JOHN P. RATHBUN.

